Dryer-added fabric conditioning products provide a better convenience to the consumer as compared to the rinse-added fabric conditioning products because they spare the consumer the requirement of having to be present right at the beginning of the rinse cycle.
There are two main types of dryer-added fabric conditioning products, namely, single use products and multiple-use products. Single use products, most commonly in the sheet form coated with a fabric conditioning active composition, calls for adding a single sheet into an automatic clothes dryer containing a wet laundry load, at the beginning of the drying cycle. Examples of this type of product are disclosed in U.S. Pat. No. 3,442,692 to Gaiser and U.S. Pat. No. 3,686,025 to Morton et al.
Multiple-use fabric conditioning products are placed in the interior of the dryer to release the fabric conditioning active to successive laundry loads. Each multiple-use product lasts many drying cycles, from a few cycles to about 50 or more cycles, and thus provides a better convenience to the consumer than single use products. One type of multiple-use products consists of a dispenser that is attached to the interior of an automatic clothes dryer, said dispenser having a permeable surface and containing a fabric conditioning active composition that is a solid at room temperature and is softenable at the operating temperature of said clothes dryer. In use, the hot operating temperature of the clothes dryer softens or melts the conditioning active which then passes through the permeable surface and is transferred to the fabric being treated by contact to provide the desired fabric conditioning benefits. Multiple-use products of this type are disclosed, e.g., in U.S. Pat. No. 3,967,008 issued Jun. 29, 1976 and U.S. Pat. No. 4,004,685 issued Jan. 25, 1977, both to Mizuno et al., and U.S. Pat. No. 4,149,977 issued Apr. 17, 1979 to Morganson et al.
Another type of multiple-use products has the fabric conditioning active not covered by a permeable surface, but is instead exposed to be transferred to the fabric. The products can be attached to the interior of the dryer, as disclosed in U.S. Pat. No. 3,696,034 issued Oct. 3, 1972, U.S. Pat. Appl. Publ. No. 2003/0192197 A1 published Oct. 16, 2003 to Griese et al., and U.S. Pat. Appl. Publ. No. 2003/0195130 A1 published Oct. 16, 2003 to Lentsch et al. The products can also be unattached and tumbled along with the clothes in the dryer interior, as is disclosed in U.S. Pat. No. 3,676,199 issued Jul. 11, 1972 to Hewitt et al. The softener active, which is preferably solid at room temperature, can soften or melt under the clothes dryer operating temperature, such as those disclosed in U.S. Pat. Nos. 3,676,199 and 3,696,034, or only softens at a temperature above the clothes dryer operating temperature, such as those disclosed in U.S. Pat. Appl. Publ. Nos. 2003/0192197 and 2003/0195130 A1.
While the multiple-use dryer-added conditioner products disclosed in the art can provide an improved convenience, they do have some performance issues. One continuing problem is the varying amount of conditioning active that is released to the fabric, as a function of the number of cycles that a product has been used. For instance, U.S. Pat. No. 4,149,977 discusses the need to control the dispensing rate or the consumption rate (Col. 6-8). One approach that has been tried to regulate the dispensing rate is to select an appropriate conditioning composition, as disclosed in U.S. Pat. No. 4,149,977 issued Apr. 17, 1979 to Morganson et al. U.S. Pat. Appl. Publ. No. 2003/0192197 discloses that the product releases the most active in the earlier drying cycles, and the shape of the product affects the dispensing rate of the product (FIG. 20, and sections [0059] to [0061]).
Perfume is routinely added to fabric conditioning compositions to be deposited to the fabric along with the fabric conditioning composition and/or via vapor transfer, in order to provide aesthetically pleasing and fabric freshening benefits. Typical perfume compounds and compositions can be found in the art including U.S. Pat. No. 4,145,184, Brain and Cummins, issued Mar. 20, 1979; U.S. Pat. No. 4,209,417, Whyte, issued Jun. 24, 1980; U.S. Pat. No. 4,515,705, Moeddel, issued May 7, 1985; and U.S. Pat. No. 4,152,272, Young, issued May 1, 1979. Each perfume composition that is added to a fabric conditioner composition comprises many perfume ingredients, with many perfume characters, and with different physical properties. In the multiple-use fabric conditioner product art, the effect of perfume on the rate of fabric conditioner active release is not known or appreciated.
Thus, there is a need to provide a multiple use fabric conditioning composition comprising different perfume forms that reduce the variation in the rate of active release, and reduces the variation in the strength and the character of the perfume during the life span of the product.
Another problem that is encountered with the multiple use fabric conditioning composition is the strong perfume odor of the composition. There is a need to deliver a desirable level of perfume intensity for the treated fabrics, without providing an amount of perfume needed that makes the perfume odor of the multiple use composition undesirably too strong.